Semiconductor devices are commonly found in modern electronic products. Semiconductor devices vary in the number and density of electrical components. Discrete semiconductor devices generally contain one type of electrical component, e.g., light emitting diode (LED), small signal transistor, resistor, capacitor, inductor, and power metal oxide semiconductor field effect transistor (MOSFET). Integrated semiconductor devices typically contain hundreds to millions of electrical components. Examples of integrated semiconductor devices include microcontrollers, microprocessors, charged-coupled devices (CCDs), solar cells, and digital micro-mirror devices (DMDs).
Semiconductor devices perform a wide range of functions such as signal processing, high-speed calculations, transmitting and receiving electromagnetic signals, controlling electronic devices, transforming sunlight to electricity, and creating visual projections for television displays. Semiconductor devices are found in the fields of entertainment, communications, power conversion, networks, computers, and consumer products. Semiconductor devices are also found in military applications, aviation, automotive, industrial controllers, and office equipment.
Semiconductor devices exploit the electrical properties of semiconductor materials. The structure of semiconductor material allows its electrical conductivity to be manipulated by the application of an electric field or base current or through the process of doping. Doping introduces impurities into the semiconductor material to manipulate and control the conductivity of the semiconductor device.
A semiconductor device contains active and passive electrical structures. Active structures, including bipolar and field effect transistors, control the flow of electrical current. By varying levels of doping and application of an electric field or base current, the transistor either promotes or restricts the flow of electrical current. Passive structures, including resistors, capacitors, and inductors, create a relationship between voltage and current necessary to perform a variety of electrical functions. The passive and active structures are electrically connected to form circuits, which enable the semiconductor device to perform high-speed operations and other useful functions.
Semiconductor devices are generally manufactured using two complex manufacturing processes, i.e., front-end manufacturing, and back-end manufacturing, each involving potentially hundreds of steps. Front-end manufacturing involves the formation of a plurality of die on the surface of a semiconductor wafer. Each semiconductor die is typically identical and contains circuits formed by electrically connecting active and passive components. Back-end manufacturing involves singulating individual semiconductor die from the finished wafer and packaging the die to provide structural support and environmental isolation. The term “semiconductor die” as used herein refers to both the singular and plural form of the words, and accordingly, can refer to both a single semiconductor device and multiple semiconductor devices.
One goal of semiconductor manufacturing is to produce smaller semiconductor devices. Smaller devices typically consume less power, have higher performance, and can be produced more efficiently. In addition, smaller semiconductor devices have a smaller footprint, which is desirable for smaller end products. A smaller semiconductor die size can be achieved by improvements in the front-end process resulting in semiconductor die with smaller, higher density active and passive components. Back-end processes may result in semiconductor device packages with a smaller footprint by improvements in electrical interconnection and packaging materials.
FIG. 1a shows a conventional semiconductor die 10 with bumps 12 formed over contact pads 14 on active surface 16. A flux material 18 is deposited over bumps 12. Substrate 20 includes contact pads 22 formed on surface 24 of the substrate. A flux material 26 is deposited over surface 24 of substrate 20. In FIG. 1b, semiconductor die 10 is bonded to substrate 20 with bumps 12 covered by flux material 18 electrically and metallurgically connected to contact pads 22 covered by flux material 26 on substrate 20. Residual flux material 18 and 26 are removed by a cleaning process. In FIG. 1c, an underfill material 28 is deposited between semiconductor die 10 and substrate 20. The bonding of semiconductor die 10 to substrate 20 occurs during a separate processing step as compared to depositing underfill material 28 between the semiconductor die and substrate.
FIG. 2a shows a conventional semiconductor die 30 with bumps 31 formed over contact pads 32 on active surface 33. A flux material 34 is deposited over bumps 31. Substrate 35 includes contact pads 36 formed on surface 37 of the substrate. A flux material 38 is deposited over surface 37 of substrate 35. In FIG. 2b, semiconductor die 30 is bonded to substrate 35 with bumps 31 covered by flux material 34 electrically and metallurgically connected to contact pads 36 covered by flux material 38 on substrate 35. Residual flux material 34 and 38 are removed by a cleaning process. In FIG. 2c, a mold underfill material 39 is deposited over and between semiconductor die 30 and substrate 35. The bonding of semiconductor die 30 to substrate 35 occurs during a separate processing step as compared to depositing mold underfill material 39 between the semiconductor die and substrate.
FIG. 3a shows a conventional substrate 40 with contact pads 41 and insulating layer 42 formed over a surface of the substrate. A non-conductive paste 43 is deposited over contact pads 41 and insulating layer 42. FIG. 3b shows semiconductor die 44 with bumps 45 formed over contact pads 46 on active surface 47. A heat tip 48 is attached to a back surface of semiconductor die 44. In FIG. 3c, semiconductor die 44 is bonded to substrate 40 with bumps 45 electrically and metallurgically connected to contact pads 41 on substrate 40 using thermocompression or reflow bonding with the aid of heat tip 48. Non-conductive paste 43 is distributed between semiconductor die 44 and substrate 40. The bonding of semiconductor die 44 to substrate 40 occurs during a separate processing step as compared to depositing non-conductive paste 43 over the substrate.
Each of the molding and bonding processes described in FIGS. 1-3 require separate manufacturing steps, which increases time and cost and introduces the potential for handling defects.